This invention relates to the thermal stabIlIzatIon of conjugated diene/monovinyl substituted aromatic hydrocarbon copolymers.
Copolymers of conjugated dienes and monovinyl substituted aromatic hydrocarbons are known and useful for a variety of purposes. However, a disadvantage of these copolymers is that upon prolonged use or processing at high temperatures the copolymers undergo deterioration. It is known to add various stabilizers to the copolymers to prevent their deterioration. However, no universal stabilizer exists, and each polymer has its own stabilization problem which requires a unique solution.
In certain applications for conjugated diene/monovinyl substituted aromatic hydrocarbon copolymers a high degree of transparency in the final product is desired. As previously mentioned, thermal stability is also a desirable property; however, the additives which enhance thermal stability in the copolymer often adversely affect the degree of transparency. Moreover, many of the stabilizers as chemicals are expensive, thus there exists the need for a stabilizer that can be cheaply made or purchased or that can be used in small amounts so as to be cost effective.
The most useful stabilizers will therefore be those which provide good thermal stability to the copolymer with the addition of small amounts of stabilizer while not adversely affecting the degree of the copolymer's transparency.